Paper machinery



Dec. 14, 1954 s-f- 2,696,766

PAPER MACHINERY Filed Aug. 21, 1952 2 $hee'ts-Shegt 1 1 WEB. BREAK 77 DETECTOR INVENTOR DONALD L. STARK ATTORNEYS 4 Dec. 14, 1954 o. STARK 2,696,765.

PAPER MACHINERY Filed Aug. 21, 1952 2 Sheets-Sheet 2 6 5 10 I INVENTOR DONALD L. STARK ATTORNEYS PAPER MACHINERY Donald Louis Stark, Appleton, Wis., assignor to The Black-ClawsonCompany, Hamilton, Ohio, a corporation of Ohio Application August 21, 1952, erial No. 305 ,5 26

12' Claims. (Cl. 92-20) This invention relates to pulping apparatus for paper making stock and the like.

The invention has particular relation to pulpingapparatus adapted for use in handling and repulping the damaged paper sheet commonly known as broke resulting from a break in the newly formed paper Web during operation of a paper machine. A practical ditficulty in the handling and pulping of broke is that while. there are extended periods when the machine is operating properly, and during which the pulping apparatus intended to handle broke is standing by, when a break in the web occurs on machines operating at the speeds of many 100 feet per minute which are relatively common in present day'manufacture, the broke accumulates correspondingly rapidly, and unless it is disposed of at a similarly rapid rate it may quickly interfere with operation of the machine and resumption of production. Furthermore, since the amount of broke accumulating from any one break in the web will vary over wide limits beyond the control of the operator, the demand on the capacity of the pulping apparatus will similarly varyover correspondingly wide limits during the times when the apparatus is in pulping operation.

Another complication in the handling of broke arises from the desirability of repulping the broke as fast as it is discharged from the machine in order to prevent its accumulation and the resulting increased difficulty of handling it. This desirable objective may be achieved by .feeding the broke directly in to pulping apparatus at a position conveniently near locations where broke is likely to accumulate, and for practical purposes the most con venient location will usually be directly beneath such locations. This arrangement, however, may be diflicult to establish with pulping apparatus of the proper size for operation at the high capacity likely to be required during an extended web break, owing to the fact that the head room beneath many paper machines is not sufiicient to receive a pulper of the optimum capacity, and especially of the proper size to receive the full width of the web of broke.

One of the primary objects of the present invention is to provide pulping apparatus which is especially adapted for handling broke from a paper machine, which is of suflicient size and capacity to receive the full width of a web of broke and to pulp such web continuously at a sufficiently rapid rate to handle the full output of broke during a web break on a paper machine, and which also requires suificiently low head room for installation in even relatively restricted spaces below a paper machine in position to receive the broke by gravity directly from the machine.

Another object of the invention is to provide stock pulping apparatus which is so constructed and arranged that it will operate with substantially equal effectiveness over a considerable range of depths of the stock and which is thus well suited for uses such as the handling of broke from a paper machine where the volume of added material to be pulped may vary as a result of causes beyond the control of the operator, as well as handling the trim which normally collects continuously during operation.

Another object is to provide stock pulping apparatus including a tub wherein the stock is adapted to be continuously circulated and which also includes a plurality of impellers located at spaced positions around the periphery of the tub for maintaining continuous circulation of the stock and inwhich the impellers are ofdifferent characteristics such that one" serves primarily for initially United States Patent "ice breaking down the larger pieces of material to be pulped while another acts primarily to defiber the solid particles in the stock as well as to submerge large material such as broke for operation thereon by theother impeller.

An additional object is to provide stock pulping apparatus as outlined above wherein the spaced impellers are located at the ends of the tub and cooperate with a mid feather to maintain the desired circulatory pattern with comparatively low power requirements.

It is also an object of theinvention to provide stock pulping apparatus wherein the tub is proportioned to receive the full width of a web of broke or like sheet material, and which includes a plurality of nozzles carried by the tub in position todischarge water jets against the sheet entering the tub forslitting the sheet and also wetting down the resulting strips of sheet material for ready pulping of the tub.

Other objects and advantages of the invention Will be apparent from the following description, the accompanying drawings and the. appended claims.

In the drawings Fig. 1 is a somewhat diagrammatic perspective view, partly broken away and in section, showing pulping apparatus in accordance with the invention;

Fig. 2 is a plan view of the pulping apparatus;

Fig. 3 is a sectional view approximately on the line 3-3 of Fig. '2;

Fig. 4 is a sectional view approximately on the line 44 of Fig. 2;

Fig. 5 is a fragmentary section on. the line 5-5 of Fig. 2; and

Fig. 6 is a section on the line 6-6 of Fig. 2.

Referring to the drawings, which illustrate a preferred embodiment of the invention, the tub of the pulping apparatus is shown as formed of tile and may also be formed of other suitable material such as concrete, cast iron or steel. It includes a bottom 10, side walls 11 and 12 and end walls 13 and 14, all supported by a common base plate 15. An elongated midfeather 16 of tile or the like extends upwardly from the tub'bottom 10 generally parallel with the side walls 11 and 12, and it cooperates with the tub walls to form an annular space within the tub through which the stock may continuously circulate. The diagonally opposite corners formed by the side and end walls are rounded as shown in Fig. 2, while the other diagonally opposite corners formed by the side and end walls are at substantially 90. The tub bottom 10 is arranged to slopev upwardly from one end of the tub to the other at an angle providing a substantial differ ence in height between its upper and lower ends, for exv ample a difference of the order of 19 inches in a tub having an overall length of approximately 17 feet, and the space between the sloping part of the tub bottom 10 and the base 16 may be readily filled in by cement or the like as indicated at 17.

The pulper tub is provided with a pair of impeller rotors 20 and 22 mounted for rotation on horizontal axes on the side walls. 11 and 12 at diagonally opposite ends of the tub. The impeller 22 is carried by a shaft and bearing assembly indicated generally at 23 and is shown as provided with a drive unit including a motor 25 and the pulley and belt indicated generally at 26. The impeller 20 is carried by a similar shaft and bearing assembly 27 and may be provided with a separate drive indicated fragmentarily at 28. As shown in Fig. 3, the axes of the two impellers are oifset vertically by a substantial margin less than the diameter of either impeller to maintain portions of their working areas invertically overlapping relation while providing pulping action through a total depth of stock greater than the diameter. of either impeller. For example, satisfactory results have been obtained with two impellers each 36 inches in diameter having their axes oflset vertically by from approximately 1 to 2 feet, and impellers of this size range otter advantages of reduced power requirements as compared with impellers of sufiicient diameter to operate through the full depth of stock.

The impellers, 20 and 22 are of similar construction, and each includes a generally circular plate or disk provided with a plurality of impeller vanes mounted around the periphery of the disk. The vanes 30 on the impeller 20 are axially extending flanges or blades arranged generally tangentially around the disk to create an outward propelling effect on the stock during rotation of the impeller. One or more larger blades 31 may be provided near the center of the impeller disk to provide a pumping effect causing the stock to flow continuously outwardly of the disk and thus setting up the desired vortical pattern in the stock adjacent the impeller.

The impeller 22 is provided with one or more inner vanes or blades 32 similar to the blade 31, and it also carries an outer plurality of blades 33 similar to the blades 30 but of substantially smaller axial dimensions. For example, in a tub of the proportions indicated, satisfactory results have been obtained with the vanes or blades 30 each of a maximum dimension of 3 inches beyond the face of the impeller plate and with the corresponding dimension of the vanes or blades 33 only approximately 1 inch. Under these conditions, the impeller 20 exerts primarily a tearing effect on the broke or other sheet material to be pulped and thus breaks down the sheet into smaller pieces, while the impeller 22 has primarily a defiberingiaction on the particles in the stock and cooperates with the other impeller to complete the pulping operation.

' With the impellers located as shown at the ends of the side walls and opposite the spaces between the ends of the midfeather and the end walls of the tub, rotation of the impellers causes the stock to be propelled radially outward in vortical patterns, and means are provided for directing the outwardly propelled stock from each impeller along the adjacent side wall of the tub to cause the stock to flow around the further end of the midfeather and into the vortex formed by the other impeller. Referring to Figs. 2 and 3, the impeller 22 is equipped with a curved shroud 35 mounted above it on the side wall 12 and cooperating with the bottom of the tub to enclose the periphery of the impeller except in the direction leading towards the opposite end of the tub. Thus with the impeller rotating in clockwise direction as viewed in Fig. 3, the blades 33 will cooperate with the shroud to propel the stock towards the opposite end of the tub where it is directed by the curved corner around the other end of the midfeather and into the vortex formed by the impeller 20.

There is a similar shroud arrangement for the impeller 20 which also serves as an extractor means for permitting stock of the properly pulped particle size to be continuously removed from the tub. At its lower end and along the side wall 11, the tub bottom is recessed to form a narrow chamber 40 which extends along approximately one-half the length of the tub and underlies impeller 20.

This chamber serves as the extraction chamber for receiving the pulped stock during continuous operation of the apparatus, and an, outlet pipe 41 is adapted for connection to a suitable pump for removing the pulped stock. The upper end of the chamber 40 is covered by a perforated screen plate 42 which includes a portion curved approximately 180 around the impeller 22 and supported at its upper end by a shroud 44. An imperforate plate 45 extends from the end wall 13 to the screen plate 42 and shroud 44 and cooperates therewith to form an upward extension of the chamber 40. 7

In operation, the screen plate 42 and shroud 44v act ;similarly to the shroud 35 in directing the outwardly propelled stock from impeller along the side wall 11 toward the opposite end of the tub and into the vortex formed by the impeller 22. At the same time, during continuous operation of the apparatus, stock which has been pulpedto the proper particle size for passage through the perforations in screen plate 42 will pass into the extraction chamber 40 for removal by way of the pipe connection 41. Inlet connections 46 and 47 are provided as shown at the opposite ends of chamber 40 for flushing this space out during cleaning of the apparatus, and another water inlet 48 leads into the space behind impeller 20 for flushing this space. An inspection opening having a suitable closure may be provided in the end wall 11 as indicated at 50.

This pulper construction is especially well adapted for mounting directly below the floor under a location on a paper machine where a web' break is likely to occur and where broke will accordingly accumulate. Thus Figs. 1 and 4 show the pulper tub directly below the floor 55 beneath the bottom roll 56 in the calender stack of a paper machine, and this pulper is especially well suited for such installation by reason of its drive arrangement with the drive motors located at the sides of the tub and thus adding nothing to the headroom requirements of the apparatus. A slot 57 is cut in the floor through which the web of broke may be admitted to the interior of the tub, and it will be noted that the top of this slot is of suflicient length to receive the entire width of the web. The pulper is accordingly always in position to receive broke whenever a web break does occur, and the broke can thus be fed directly into the pulper as fast as it accumulates.

In order to assure adequately rapid disposal of broke when a web break occurs, it should be pulped with maximum speed, and the pulping apparatus of the invention is especially adapted for such operation. As shown, the slot 57 is located above the space between the midfeather and the top wall 12, so that the broke material entering the tub is delivered into the path of stock from the defibering impeller 22 to the impeller 20, and thus the new material is subjected to the tearing action of the impeller 20 before it is acted upon by the defibering impeller 22. In addition, nozzles are provided within the tub which wet the broke down into the tub and which also may operate to slit the web of broke into multiple strips as a further aid to rapid pulping. A header pipe 60 is connected at 61 with a source of water under suitable pressure, and a plurality of nozzles 62 extend from header pipe 60 through the back wall 12 of the tub just below the top of the tub. If the water is supplied to header 60 at sufiicient pressure for discharge from the nozzles 62 in the form of high speed jets, it will tend to slit the web into strips, and the resulting stripped material will be quickly torn by the impeller 20 into pieces of adequately smaller size for ready defibering when they encounter the impeller 22. p

This pulping apparatus may also be connected to receive the trim cut from the newly formed paper sheet by theusual trimming mechanism at the delivery end of the paper machine. Referring to Figs. 2 and,4, inlets 65 extend through the front wall 11 of the tub, one of these inlets being shown near each end of the tub, and they are adapted for connection by tubes 66 with the trimming stations to provide for blowing the trim directly into the tub. A water inlet nozzle 67 is provided just below each v of the trim inlets 65 for connectionto the water supply ill) in order to wet down the trim as it enters the tub.

In the .use of this pulper for handling broke in an installation such as described in connection with Fig. 1, during normal operation of the paper machine, the pulper will be standing by or can be connected as shown for continuously receiving the trim, in which case the drive motor for impeller 20 will be operated at adequate speed for pulping the trim and the tub will be partly filled with water to a sufiicient height to take care of the trim and to accomplishinitial dilution of the consistency of the suspension therein when broke occurs and is fed into the tub. Inorder to maintain the water level at the proper depth for pulping at all times, a suitable pressure responsive liquid level control, indicated diagrammatically at 70, may be connected with the tub as by means of a pipe 71 opening into the lowermost portion of the tub, and the level control 70 may also be connected to control a valve 72 in the supply pipe for the nozzle header 65. Similarly,

the motor 25 for impeller 22 may be controlled by a switch 75 operated in response to actuation of a web break detector indicated diagrammatically at 77.

Preferred results in'operation are obtained if the liquid level control 70 is of the commercially available type which operates to open the valve 72 so long as the liquid level within the tub is increasing above a predetermined level. Under these conditions, whenever material to be pulped is added to the tub, either as a result of a web break or when material to be pulped is directly added from some other source, the increase in the liquid level resulting from the addition of this solid will actuate the level control 70 to open valve 72 and thus cause addition of sufiicient water to the tub to maintain the suspension therein at proper consistency for pulping. The motor 25 for impeller 22 will similarly start substantially simultaneously with a break in the web to assure efiective pulping of the broke as it feeds into the tub.

Rapid and eflicient pulping is also added by the operation of the water jets discharged by the nozzles 67, since in addition to slitting the sheet, they wet it down into the tub.

v In addition, with the charging opening defined by the slot 57 located as shown above the space between the midfeather and the tub wall 12, the added material first be subjected to the breaking or tearing action'of the impeller 20 so that it is reduced to smaller pieces before reaching the defibering impeller 22 which completes the pulping operation.

This arrangement and cooperative relation of the several parts assures the rapid and efiicient pulping necessary in order to dispose of the rapidly accumulating broke with economical power requirements. As fast as the added sheet is reduced to the proper particle size for passage through the perforations in the screen plate 42, it is received into the chamber 40 for removal by way of outlet pipe 41, and this action is also facilitated by the arrangement of the screen plate 42 directly in the path of the outwardly propelled stock from the impeller 20. Thus the stock is pulped and removed at a rapid rate to dispose of the entire output of broke at a rate sufficiently close to the production rate of the paper machine to broke at any point.

A further desirable feature of this pulping apparatus is its ability to operate with equal effectiveness even though charged with materially less stock than its full capacity. Thus when fully charged, the desired continuous circulation will automatically result from the cooperative relation of the impellers and their respective shrouds. However, the pulper will operate satisfactorily even when the level of stock therein is not sufiicient to cover the higher impeller 22. Under such conditions, the sloping bottom of the tub aids in establishing the desired continuous circulation, since the impeller 20 will propel the stock from the deep end of the tub tothe shallow end and thus cause it to flow around the end of the midfeather and back again to the deep end of the tub, and this action may be made use of as described for pulping the trim during normal paper machine operation.

This pulping apparatus also offers important advantages from the standpoint of low power requirements, especially in viewof its ability to handle trim effectively with a single impeller. In addition, with the parts of the sizes noted above, the power requirements when both impellers are in operation are relatively low, namely of the order of 40 to 50 horsepower on bond papers and similarly relatively soft stocks if the tub includes a midfeather as shown to aid in establishing the desired circulatory pattern of the stock in the tub. If the midfeather is omitted, a similar pattern can be maintained by the cooperative action of the impellers with their respective shrouds and the curved corners of the tub,

but the power requirements may range somewhat higher, for example, to approximately 75 horsepower per impeller on similarly soft stocks.

It will be apparent that while the pulping apparatus of the invention is especially well suited for use in handling broke in installations of the type described, it is not limited to such use and is equally well adapted for handling other batch or continuous pulping operations. Furthermore, while the arrangement of the component parts of the pulper is especially advantageous for constructing the tub of a length and size to fit below a paper machine in position to receive the full width of the web of broke therefrom, these proportions may be varied to suit particular installations, and also the overall size of the tub is subject to change in accordance with the width of the web of broke which it is primarily intended to handle.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A pulper of the character described for paper making stock comprising an elongated tub having a bottom and generally vertical side and end walls, a pairof impellers mounted for rotation on horizontal axes on said side walls at diagonally opposite ends of said tub prevent undesirable accumulation of and including means for applying an outward propelling the adjacent side wall of said tub to cause said stock to flow in a circulatory pattern around the interior of said tub andinto the vortex formed by the other said impeller.

2. A pulper of the character described for paper making stock comprising an elongated tub having a bottom H and generally vertical side and end walls, a midfeather mounted generally centrally of said tub in generally parallel relation with said side walls and cooperating with said tub to form an annular space therewithin, a pair of impellers mounted for rotation on horizontal axes on said side walls at diagonally opposite ends of said tub and including means for applying an outward propelling force on said stock, means for rotatingsaid impellers to propel said stock outwardly in vortices coaxial with said respective impellers, and means for directing said outwardly propelled stock from each said impeller along the adjacent side wall of said tub to cause said stock to flow around the further end of said midfeather and into the vortex formed by the other said impeller.

3. A pulper of the character described for paper making stock comprising an elongated tub having a bottom and generally vertical side' and end walls, a pair of impellers mounted for rotation on horizontal axes on 'saidside walls at diagonally opposite ends of said tub and including means for applying an outward propelling force on said stock, means for rotating said impellers to cause said stock to be propelled outwardly therefrom, means for directing said outwardly propelled stock from said impellers along said side walls of said tub to cause said stock to flow continuously around the interior of said tub, means forming a chamber in the lower part of said tub below one said impeller, and a perforate screen separating said chamber from the interior of said tub and located in the outward path of said stock from one said impeller for admitting to said chamber pulped stock of particle sizes capable of passage through the perforations in said screen.

4. A pulper of the character described for paper making stock comprising an elongated tub having a bottom and generally vertical side and end walls, a pair of impellers mounted for rotation on horizontal axes on said side walls at diagonally opposite ends of said tub, said impellers having blades thereon for applying an outward propelling force on said stock, means for rotating said impellers to propel said stock outwardly in vortices coaxial with said respective impellers, said blades on one said impeller being of substantial axial dimensions for breaking up large pieces of material to be pulped, said blades on the other said impeller being of substantially lesser axial dimensions for defibering action on said pulp,

, side walls at diagonally opposite ends of said tub and including means for applying an outward propelling force on said stock, means for rotating said impellers to propel said stock outwardly in vortices .coaxial with said respective impellers, said impellers being positioned with the respective axes thereof in vertically offset relation by a predetermined limited distance maintaining portions of both said impellers in vertically overlapping relation while providing pulping action through a depth of stock greater than the diameter of either said impeller, and means for directing said outwardly propelled stock from each said impeller along the adjacent side wall of said tub to cause said stock to flow around the interior of said tub and into the vortex formed by the other said impeller.

6. A pulper of the character described for paper making stock comprising an elongated tub having a bottom and generally vertical sidevand end walls, a pair of im pellers mounted for rotation on horizontal axes on said "as-sates tively large pieces of material to be pulped, said blades on the second said impeller being of substantially smaller 'axial dimensions for defibering action on said pulp, means for directing said outwardly propelled stock from each said impeller along the adjacent side wall of said tube to cause said stock to flow in a circulatory pattern around the interior of said tub and into the vortex formed by the other said impeller, and means defining a charging opening for said tub locatedin position to effect delivery of the material to be pulped into the path of stock from said second impeller to said first impeller and thus to subject said material to said breaking actionof said first impeller before reaching said second impeller.

1 7. A pulper of the character described for paper making stock comprising an elongated tub having a bottom and generally vertical side and end walls, a midfeather mounted generally centrally of said tub in generally parallel relation with said side walls and cooperating with said tub to form an annular space therewithin, a pair of impellers mounted for rotation on horizontal axes on said side walls at diagonally opposite ends of said tub and including means'for applying an outward propelling force on said stock, means for rotating said impellers to propel said stock outwardly in vortices coaxial with said respective impellers, means for directing said outwardly propelled stock from each said impeller along the adjacent side wall of said tub to cause said stock to flow around the further end of said midfeather and into the vortex formed by the other said impeller, and said bottom of said tub being inclined from one end thereof to the other to provide for continuous circulation of stock in said tub at depths thereof insufficient to cover said impeller at the higher endof said tub bottom.

8. A pulper of the character described for paper making stock comprising an elongated tub having a bottom and generally vertical side and. end walls, a pair of impellers mounted for rotation on horizontal axes on said side walls at diagonally opposite ends of said tub and including means for applying an outward propelling force on said stock, means for rotating said impellers to propel said stock outwardly in vortices coaxial with said respective impellers, means for directing said outwardly propelled stock from each said impeller along the adjacent side wall of said tub to cause said stock to flow around the interior of said tub and into the vortex formed by the other said impeller, said bottom of said tub being inclined from one end thereof to the other to provide for continuous circulation of stock in said tub at depths thereof insufficient to cover said impeller at the higher end of said tub bottom, means forming a chamber in the lowermost portion of said tubbottom-below the adjacent said impeller, and a perforate screen separating said chamber from the interior of said tub and located in the outside path of stock from said adjacent impeller for admitting to said chamber pulped stock of particle I a cent side "w ll of said tub midfeather into the'vortex formed by the other'said a impeller. a

10. A. pulper of the character described for paper making' stock comprising an elongated tub having a bottom and generally vertical side and end walls, a midfeather mounted generally centrally of said tub in generally parallel relation with said side walls and cooperating with said tub to form an annular space therewithin, a pair of impellers mounted for rotation on horizontal axes on 7 said side walls at diagonally opposite ends of said tub,

said impellers having blades thereon for applying an outward propelling force on said stock, means for rotating said impellers to cause said stock to be propelled outwardly therefrom, said blades on the first said impeller being of substantial axial dimensions for breaking down relatively large pieces of material to be pulped, said blades on the second said impeller being of substantially smaller axialdimensions for defibering action on said pulp, means for directing said outwardly propelled stock from each said impeller along the adjacent side wall of said tub to cause said stock to flow around the further end of said midfeather and into the vortex formed by ing for said tub generally parallel with and located above and between saidmidfeather and the side wall of said tub supporting said second impeller, said opening extending substantially the full length'of said tube to receive therethrough the full width of a web of material to be pulped and to deliver said web into the path of stock from said second impeller to said first impeller for operation thereon by said first impeller before reaching said second impeller, and a plurality of nozzles adapted to be supplied with water under pressure and carried by said tub in aligned and spaced relation below said open- -ing in position to discharge water jets against said web received through said opening to slit and wet down said and generally vertical side and end walls, a midfeather mounted generally centrally of said tub in generally parallel relation with said side walls and cooperating with said tub to form an annular space therewithin, a pair of impellers mounted for rotation on horizontal axes on said side walls at diagonally opposite ends of said tub and including means for applying an outward propelling force on said stock, means for rotating said impellers to propel said stock outwardly in vortices coaxial with said respective impellers, means forming a chamber in the bottom and one end of said tub in radially outwardly spaced relation with one said impeller, a perforate screen separating said chamber from the interior of said tub,

-said screen extending below and partially around said one impeller in the outward path of stock from said im- Qpeller for admitting to said chamber pulped stock of and generally vertical side and end walls, a midfeather,

mounted generally centrally of said tub in generally parallel relation with said side walls and cooperating with said tub to form an annular space therewithin, a pair of impellers mounted for rotation on horizontal axes on said side walls at diagonally opposite ends of said tuband including means for applying an outward propelling force on said stock, means defining a charging opening for said tub generally parallel with and located above and in laterally spaced relation with said midfeather,

particle sizes, capable of passage through the perforations in said screen While directing the remainder of said stock along the adjacent side Wall of'said tub, and means associated with the other said impeller for directing said outwardly propelled stock therefrom along the other side wall of said tub for cooperation with said screen to cause said stock to fiow continuously around the ends of said midfeather and into the vortices formed by said impellers.

12. A pulper of the character described for paper making stock comprising an elongated tub having a bottom and generally vertical side and end walls, said side and end walls being arranged at substantially right angles to each other at one pair ofvdiagonally opposite corners of said tub, a pair of impellers mounted for rotation on horizontal axes on said side walls adjacent said right said opening extending substantially the full length of said tub to receive therethrough the full width of a web of material to be pulped, a plurality of nozzles adapted to be supplied with water under pressure and carried by said tub in aligned and spaced relation below said opening in position to discharge water jets against said Web received through said opening to slit and wet down said web, means for rotating said impellers to effect pulping of said slit wet material while propelling said stock outwardly therefrom in vortices coaxial with the respective said impellers, and means for directing-said outwardly propelled stock from each said impeller along the adjaplying an outward propelling force on said stock, means for rotating said impellers to propel said stock outwardly in vortices coaxial with the respective said impellers, means for directing said outwardly propelled stock from each said impelleralong the adjacent side wall of said tub, and the other pair of diagonally opposite corners being cylindrically curved to redirect the stock flowing thereto along the adjacent said side wall through approximately ninety degrees and into the vortex formed by I lithe other said impeller.

(References on following page) References Cited in the file of this patent Number UNITED STATES PATENTS Name Date Cram Nov. 20, 1928 5 Grewin May 22, 1934 Cowles Dec. 9, 1941 Nash Dec. 14, 1943 Number FOREIGN PATENTS Country Date 

